Voltage regulator-for transformers



A. ROOTH VOLTAGE REGULATOR FOR TRANSFORMERS May '3, 1927. 1,626,970

Filed March 17 1926 AdoZf 77 00272 @mm JZWEr Yg rammed May 3, 1927.

UNITED STATES PATENT OFFICE.

ADOLF BOOTH, OF LUDVIK A, SWEDIIN, ASSIGNOR 1'0 ALLMANNA SVENSKA ELEK- TRISKA AKTIEBOLAGET, OF VASTERAS, SWEDEN, A CORPORATION OI SWEDEN.

VOLTAGE REGULATOR IOR TRANSFORMERS. v

Application filed March 17, 1926, Serial No. 95,581, and in Sweden March 18, 1925.

Voltage re ulators for transformers in which the shifting of the outgoing leads from one tap to another shall be possible during service, have hitherto been provided either with separate contactors for the different taps, or with a row of stationary contacts which by means of a sliding contact moving thereover can be connected, one after another, to a contact rail. The latter his connected to an outgoing lead, either to a line or to another transformer leg, depending upon whether the regulating is effooted at the terminals or at the neutral point. In passing from one tap of the transformer to another, a resistance is first introduced between them, in order neither to break the current nor to short-circuitany part of the transformer. lVhen sliding contacts have been used, the said resistance has either been movable together with these or it has been stationary and controlled by means of separate contacts' In the latter case, the resistance has generally been inserted between two contact rails running along the whole row of contacts. \Vhen the number of the taps is relatively large, both the aforesaid'types of arrangement have resulted in constructions requiring much space.

According to the present invention thev taps of the transformer are alternately connected to two rows of stationary contacts, each row being traversed by a sliding con tact which connects it to a contact rail. Between these two contact rails, the resistance may be connected. In this way, 'by using four contact rows or rails side by side, the apparatus will obtain only about half of the length as when three rows or rails are used in the known way, and about one third of the length required for two rows (with movable resistance). lVhether thecontact rows are straight or circular, the dimensions of the regulator will be much more convenient, as soon as the number of taps reaches a certain value. Other advantages of the invention will be apparent from the following description of a preferred form thereo I The accompanying drawing shows :1 diagram of connections of a voltage regulator accordin to the invention. r

Referring to the drawing, T represents a transformer winding having nine taps connected to contacts 1-9. The latter are arranged in two rows, those having odd numbers in one and those having even numbers in another row. Along the former row runs a contact rail S and along the latter a corresponding rail S The contacts 1-9 may be alternately connected to these rails by means 00 of sliding contacts P P The outgoing lead L is connected alternately to the rails S S either directly or through a resistance,'by means of a sliding contact K, as will be more fully described hereinafter. In the form shown, the resistance is divided in two portions, R and R connected respectively to the two rails S S In the position shown in the drawing, the outgoing lead is connected to the tap 4, while the shifting to the next lower tap has been prepared by connecting the tap 5 to the rail S throughthe sliding contact P The said shifting comprises the following operations. The left branch K of the sliding contact K, which has made contact before only with the contact d directly connected to the rail S now also touches the contact 0 which .is connected to the rail S through the. resistance R Thereby no immediate alteration I of the voltage conditions is caused.- Soon after, however, the branch K leaves the contact d, and about simultaneously the branch K reaches the contact I) which is connected to the rail S, through the resistance'R,. In this osition, the portion of the transformer win ing lying between the ta s 4: and 5 is closed over a resistance R,+ while the outgoin lead is connected to the middle point 0 said resistance and has thus practlcally the medium Volta e between 4 and 5. At the next instant, t e' resistance R, is short-circuited between a and 6, whereby the voltage on the outgoing lead' sinks ractically to the voltage on 5, and imme iately afterwards the connection at c is broken.

Finally the resistance R is disconnected by placing the branch K right opposite a.

In making the next step in volt -lowering direction, the slidingcontact 2 is first placed on the tap-contact 6, whereupon the contact K is rotated back to the position shown in the drawing: when the procedure will be analogous to t at just described.

By the division of the resistance into'two parts R and R,, which has been made possible by the division of the tap contacts, the advantage is gained that the resistance causing volta e drop durin the shifting operation will, only half 0 that over w ie the 0 intermediary portion of the transformer is closed during the major part of said operationI Further the voltage on the outgoing lead will have an intermediate value between the beginning and end values. The voltage regulation will thus be much more soft than without this division of the resistance. The invention, is, however, also applicable in the latter case, it being possible to locate the resistance as a whole between a and (l or between a and b.

I claim as my invention 1. In voltage regulators for transformers, a transformer winding having a series of taps, two rows of fixed contacts alternately connected to said taps, contact rails running along said rows, slidable contacts adapted to connect said rails respectively to the contacts of said rowsfa resistance, an outgoing lead, and contacts adapted to connect said outgoing lead alternately to said contact rails and alternately over and past said resistance;

2. In voltage regulators for transformers, a transformer windin having a series of taps, two rows of fixed contacts alternately connected to said taps, contact rails running along said rows, slidable contacts adapted to connect said rails respectively to the contacts of said rows, resistances connected to said rails, an outgoing lead, and contacts adapted to connect said outgoinglead alternately to either of said rails directly and over one of said resistances.

In testimony whereof I have signed my 35 name to this specification.

ADOLF BOOTH. 

